Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Salmonella typhimurium contains three electrophoretically separable enzyme activities that hydrolyze N-acetyl phenylalanine beta-naphthyl ester (NAPNE). One of these enzymes is an endoprotease, protease I. Mutations at a locus apeA near purE lead to loss of this enzyme. We have found that N-acetyl leucine alpha-naphthyl ester (NALNE) is not hydrolyzed by protease I but is a good substrate for the other two activities. Using NALNE as a chromogenic substrate to screen colonies growing on agar, we have isolated mutants (apeB) that simultaneously lose both of the two other esterase activities. The chromosomal positions of apeB and nearby markers in the proC-purE region have been determined using both phage P1 and phage P22 mediated transduction. The observed order is proC thiC apeB apt apeA purE. Strains lacking all three activities (apeA apeB double mutants) have been constructed and have growth rates similar to wild-type strains.
Mol Gen Genet 1978 Aug 04
PMID:Acylaminoacid esterase mutants of Salmonella typhimurium. 36 40

A procedure for the large-scale isolation of leucyl-tRNA synthetase from E. cole MRE 600 is described: The enzyme was purified about 320-fold to homogeneity by precipitation with cetyl-trimethyl-ammonium bromide, two consecutive chromatographies on DEAE-cellulose and three on hydroxyapatite with an over-all yield of 4%. The molecular weight of leucyl-tRNA synthetase from E. coli MRE 600 was found to be 99 000 daltons. Bindings studies by ultracentrifugation and equilibrium partition showed that the enzyme binds leucine, leucyl-adenylate and tRNA Leu, each in a 1 : 1 stoichiometry. For ATP only a very weak binding to the enzyme could be observed, which did not allow the evaluation of the complex stoichiometry. The presence of ATP was not required for the binding of leucine or tRNA to leucyl-tRNA synthetase from E. coli MRE 600.
Mol Cell Biochem 1979 Apr 02
PMID:Isolation and binding properties of leucyl-tRNA synthetase from Escherichia coli MRE 600. 37 93

Binding of 125I-LH-RH and its analogue, 125I-6-D-Leu-10-Des-Gly-Ethylamide-LH-RH (6-D-LH-RH) in male serum was studied in 10 healthy males and in 11 patients with idiopathic gonadotropin deficiency (IGD) before and during treatment with 6-D-LH-RH. Using either equilibrium dialysis (A) or ethanol precipitation (B) 13.57 +/- 0.69% (A) or 19.32 +/- 1.73% (B) of LH-RH and 7.12 +/- 0.86% (A) or 14.56 +/- 1.06% (B) of the analogue were in the bound form, without difference between normal subjects and IGD. Capacity of this binding was high (greater than 9 less than 18 mu-Mol LH-RH/0.06 mMol of protein), affinity very low, and the binding almost completely disappeared following removal of albumins by affinity chromatography. Chronic treatment with 6-D-LH-RH did not alter these binding characteristics. These observations suggest non specific albumin binding of LH-RH in male serum and stress the role of this decapeptide as a rapid modulating regulator of gonadotropin secreting system.
 ...
PMID:Binding of luteinizing hormone releasing hormone to human serum proteins--influence of a chronic treatment with a more potent analogue of LH-RH. 38 Nov 40

A number of Salmonella typhimurium ilv::Tn10 insertion strains were used to analyze the Salmonella ilv gene cluster. Tn10 generated ilv deletion mutants were employed in mapping experiments to conclusively define the gene order as ilvG-E-D-A-C. Examination of ilv enzyme levels confirms that the direction of transcription of ilvGEDA is from ilvG to ilvA. The major control locus, designated ilvO, is located before ilvG forming an ilvOGEDA transcriptional unit that is multivalently repressed by isoleucine, valine and leucine. Two internal promoters, one before ilvE and anonother before ilvD, are identified and are shown to provide repressed levels of the ilvE, D and A gene products. Possible regulation of transcription from these promoters in response to isoleucine limitation is discussed in terms of attenuation.
Mol Gen Genet 1979
PMID:Genetic organization of the Salmonella typhimurium ilv gene cluster. 39 8

1. Studies were performed to investigate the metabolic fate of dipeptides when administered intravenously in rats. Glycyl-leucine, glycylglycine or glycylsarcosine was injected into the jugular vein. The plasma disappearance rate after the peak plasma concentrations was most rapid for glycyl-leucine and least rapid for glycylsarcosine. 2. During urine collection for 40 min, trace amounts of glycyl-leucine and glycylglycine and 13% of the injected glycylsarcosine were excreted. 3. Neither glycylglycine nor glycyl-leucine was detected in the liver, muscle, intestinal mucosa or renal cortex, but concentrations of glycine or leucine, or both, in these tissues were increased after each injection. In contrast, glycylsarcosine was recovered in all these tissues with concentrations in the renal cortex being far greater than in any other tissue, but sarcosine was found only in the renal cortex and intestinal mucosa. 4. The changes in plasma concentrations of free amino acids, glucose and glucagon, and tissue concentrations of free amino acids, were similar after the intravenous administration of glycyl-leucine and an equimolar mixture of free glycine and leucine. However, the amount of insulin secreted during the 40 min after glycyl-leucine injection was 1-6 times that produced after the injection of the corresponding amino acid mixture. 5. Results show that, within the present experimental conditions, the intravenous administration of dipeptides is as effective as that of the corresponding free amino acids in enriching the tissue pools of amino acids. It is suggested that efficient hydrolysis by cellular enzymes prohibits accumulation of intact dipeptides in body tissues.
Clin Sci Mol Med 1977 Feb
PMID:Metabolism of intravenously administered dipeptides in rats: effects on amino acid pools, glucose concentration and insulin and glucagon secretion. 40 46

Cytosine residues in 32P-labeled E. coli tRNA Leu 1 were modified by treatment of the tRNA with the semicarbazide-bisulfite reagents [Hayatsu, H. (1976) Biochemistry 15, 2677-2682]. Analysis of the modification sites showed that only four cytidine residues, i.e. C35, C53, C85 and C86, reacted. They were identical with the cytidines of this tRNA accessible to methoxyamine [Chang, S. E. and Ish-Horowicz, D. (1974) J. Mol. Biol. 84, 375-388] and the accessibility was consistent with the conformational features recognized for tRNA in general. The rapidity and the simple nature of this modification demonstrate that the semicarbazide-bisulfite reaction is a useful tool in studying conformations of polynucleotides.
 ...
PMID:A rapid cytosine-specific modification of E. coli tRNA Leu 1 by semicarbazide-bisulfite, a probe for polynucleotide conformations. 40 97

The leucine genes of Bacillus subtilis have been cloned directly from the chromosomal DNA into Escherichia coli leuB cells by selection for the Leu+ phenotype using RSF2124 as a vector plasmid. The hybrid plasmid designated RSF2124-B.leu contained a 4.2 megadalton fragment derived from B. subtilis DNA, including the leu genes. The fragment had one site susceptible to EcoRI* and another site susceptible to BamNI endonuclease. Among the three fragments produced by EcoRI* and BamNI endonucleases, the 1.2 megadalton fragment had the ability to transform B. subtilis leuA, leuB and leuC auxotrophs to leu+. However, B. subtilis ilvB and ilvc auxotrophs were not rescued even by the whole 4.2 megadalton fragment present in the hybrid plasmid. beta-Isopropylmalate dehydrogenase (leuB gene product) activity found in E. coli cells containing the hybrid plasmid was about 60% of that in E. coli wild type cells, despite the high copy number (7.8) of the plasmid per chromosome observed.
Mol Gen Genet 1978 Jan 17
PMID:Cloning of Bacillus subtilis leucina A, B and C genes with Escherichia coli plasmids and expression of the leuC gene in E. coli. 41 24

A series of five alternating poly(leucyl-lysyl) samples with varying amounts of L-and D-residues randomly distributed along the chain, but evenly shared out amongst leucyl and lysyl residues were synthesized by condensation of a mixture of the four diastereoisomeric dipeptide p-nitro-phenylesters. Their behavior in aqueous solution at various ionic strengths was studied by infrared spectroscopy which allowed measurement of the total amount of beta-structures, and by circular dichroism which gives the excess of L-residues over D-residues in the same structures. Comparison with the properties of the all L-poly(Lys-Leu-Lys-Leu) shows that incorporation of a few D-residues in a L-chain seems to reduce the width of the beta-sheets obtained in presence of salt. Higher proportions of D-isomers prevent the coil leads to beta transition from occurring when the ionic strength is increased except for segments containing at least 6 to 7 adjacent residues of the same configuration.
J Mol Evol 1979 Jun 08
PMID:Beta-structures of polypeptides with L-and D-residues. Part I. Synthesis and conformational studies. 45 71

Cell-free protein synthesizing systems were prepared from the livers of chick embryos at selected ages and the characteristics of individual fractions were compared. While polysomes showed decreasing size with older embryos, isolated polysomes did not differ significantly in amino acid incorporating activity when assayed with standard cell sap. When assayed with standard polysomes, cell sap activity decreased with increasing developmental age whether incorporation was measured using (3H)lysine, (3H)leucine, or [3H]aminoacyl-tRNA. Free amino acid concentrations in the cell sap showed reproducidble independent variation during development which was taken into consideration in calculating net amino acid incorporation. A larger increase in ribonuclease activity was observed during development; however, nuclease inhibitor activity was absent before day 15 but increased thereafter. Aminoacyl-tRNA sythetase activity did not vary significantly. It is proposed that the observed changes in the rate of cell-free protein synthesis result not only from increasing ribonuclease activity with increasing developmental age but also from changes in the activity of other soluble factors.
Mol Cell Biochem 1979 Apr 02
PMID:Polymorphism in fowl serum albumin. VI. Changes in in vitro protein synthesizing activity in developing embryonic fowl liver. 46 Jan 76

Three forms (E1, E2 and E3) of leucyl-tRNA synthetase (LeuRS) were separated by DEAE-cellulose chromatography of total aminoacyl-tRNA synthetases from cow lactating mammary gland. The method of purification of all three components is described. E1 is a dimeric molecule (alpha 2) of molecular weight 182 000. Two other forms of molecular weight 67 000 and 64,000 consist of a single polypeptide chain as determined by polyacrylamide gel electrophoresis. Optimum conditions and kinetic parameters of leucyl-tRNA formation were studied for every enzyme form. The low values of Vmax and thermostability are characteristic of E3. All forms of LeuRS interact with 6 isoaccepting tRNA(Leu) from lactating mammary gland and can activate leucine in the absence of tRNA. E2 and E3 are supposed to derive from the native enzyme by endogenous proteolysis. The physico-chemical properties of native LeuRS from lactating mammary gland are compared with those of LeuRS's from other sources.
Mol Biol (Mosk)
PMID:[Purification and properties of leucyl-tRNA synthetase from the cow mammary gland]. 57 75


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>